This invention relates to a television camera apparatus, and more particularly to a color television camera apparatus with a self-diagnosis function.
During the operation of a conventional color television camera apparatus, an adjustment which is called a "routine adjustment" is automatically carried out by means of an adjusting means built into the apparatus. In this type of adjustment a predetermined test chart such as a registration chart is picked up by the camera apparatus and video signals from the camera corresponding to the predetermined chart are supplied to a signal processing section incorporated in the apparatus. In the signal processing section the video signals are subjected to adjustments such as gain control, gamma correction, pedestal level correction. The video signals thus processed are supplied to a data detecting section. In this section adjustment data is detected from the video signal and is supplied to an arithmetic operation section in which correcting data is calculated by comparing the adjustment data with a reference data previously stored in a memory section. The correcting data is converted by a correction signal circuit into an analog correcting signal and then is supplied to a defecting circuit and also to a signal processing circuit. Further, the correcting data is stored in the memory section.
As stated above, a video signal control system for a color television camera apparatus has control sensitivities corresponding to each adjustment item. In the course of time, however, the circuits in the control system are subjected to natural deterioration and changes occur in the circuit constants. Minor errors, though individually negligible, may, in the course of time, add up to such a degree as to manifest themselves as a sudden debasement of control accuracy in the system with resultant failure in the operation of the camera apparatus.
A conventional method of checking the operation of the video signal control system of the color television camera apparatus consists of examining the individual circuits of the system one by one in which the output conditions thereof are detected for possible fault in the system operation. The power source is also checked. However, such a method requires the use of certain measuring instruments. Furthermore, this checking method is not preventive. That is, it cannot forecast the occurrence of trouble and therefore corrective action can be taken only after the abnormality in the video signal output or in the power source voltage is observed.